Horwitz Barry, Warner Brent, Fitzer Julie, Tagamets M-A, Husain Fatima T, Long Theresa W
Brain Imaging and Modeling Section, National Institute on Deafness and Other Communications Disorders, National Institutes of Health, Building 10, Room 6C420, MSC 1591, Bethesda, MD 20892, USA.
Philos Trans R Soc Lond B Biol Sci. 2005 May 29;360(1457):1093-108. doi: 10.1098/rstb.2005.1647.
Viewing cognitive functions as mediated by networks has begun to play a central role in interpreting neuroscientific data, and studies evaluating interregional functional and effective connectivity have become staples of the neuroimaging literature. The neurobiological substrates of functional and effective connectivity are, however, uncertain. We have constructed neurobiologically realistic models for visual and auditory object processing with multiple interconnected brain regions that perform delayed match-to-sample (DMS) tasks. We used these models to investigate how neurobiological parameters affect the interregional functional connectivity between functional magnetic resonance imaging (fMRI) time-series. Variability is included in the models as subject-to-subject differences in the strengths of anatomical connections, scan-to-scan changes in the level of attention, and trial-to-trial interactions with non-specific neurons processing noise stimuli. We find that time-series correlations between integrated synaptic activities between the anterior temporal and the prefrontal cortex were larger during the DMS task than during a control task. These results were less clear when the integrated synaptic activity was haemodynamically convolved to generate simulated fMRI activity. As the strength of the model anatomical connectivity between temporal and frontal cortex was weakened, so too was the strength of the corresponding functional connectivity. These results provide a partial validation for using fMRI functional connectivity to assess brain interregional relations.
将认知功能视为由网络介导，已开始在解释神经科学数据方面发挥核心作用，并且评估区域间功能和有效连接性的研究已成为神经影像学文献的主要内容。然而，功能和有效连接性的神经生物学基础尚不确定。我们构建了具有多个相互连接的脑区的神经生物学现实模型，用于视觉和听觉物体处理，这些脑区执行延迟匹配样本（DMS）任务。我们使用这些模型来研究神经生物学参数如何影响功能磁共振成像（fMRI）时间序列之间的区域间功能连接性。模型中纳入了变异性，包括个体间解剖连接强度的差异、扫描间注意力水平的变化以及与处理噪声刺激的非特异性神经元的逐次试验相互作用。我们发现，在DMS任务期间，颞叶前部和前额叶皮质之间整合突触活动的时间序列相关性比在对照任务期间更大。当整合突触活动通过血流动力学卷积以生成模拟fMRI活动时，这些结果不太明显。随着颞叶和额叶皮质之间模型解剖连接强度的减弱，相应功能连接的强度也减弱。这些结果为使用fMRI功能连接性评估脑区间关系提供了部分验证。
